Conventionally, as the above lighting unit, one example is proposed that is shown in FIG. 8. As shown in FIG. 8, a lighting unit 1 includes: a plurality of lighting loads 2 arranged in various parts of a vehicle; a control unit 3 as a first control device for controlling the plurality of lighting loads 2; and a wire harness 8 for connecting the plurality of lighting loads 2 with the control unit 3.
Each of the plurality of lighting loads 2 is composed of a red (R) light source 21, a green (G) light source 22, and a blue light source 23. By adjusting brightness of the R light source 21, the G light source 22, and the B light source 23, the lighting color can be changed. For example, the control unit 3 is composed of a microcomputer and the like.
The wire harness 8 is composed of an electric wire commonly connected to one ends of the plurality of lighting loads 2, and a plurality of electric wires respectively connected to the other ends of the R light sources 21, the G light sources 22, and the B light sources 23 composing the lighting loads 2. In this way, when the other ends of the light sources 21 to 23 are separately connected to the control unit 3, the plurality of lighting loads 2 can be controlled independently.
However, in the lighting unit 1 shown in FIG. 8, the number of the electric wires composing the wire harness 8 is required to (the number of the lighting loads 2× the number of the light sources 21 to 23 composing the lighting load 2). Therefore, there is a problem that the control unit 3 may be upsized, the wire harness 8 may be enlarged, and the weight of the wire harness 8 may be increased due to increase of the number of electric wires. Further, because the control unit 3 directly controls power supply to the lighting loads 2, there is a problem that heavy load is applied to the control unit 3. As shown in FIG. 9, when the number of the lighting loads 2 is increased, these problems are escalated.
Therefore, as shown in FIG. 10, it is considered that the other ends of the R light sources 21, the other ends of the G light sources 22, and the other ends of the B light sources 23 of the lighting loads 2 are commonly connected together. However, in this case, the control unit 3 is prevented from being upsized, and the wire harness 8 is prevented from being enlarged and weighted, but the lighting loads 2 cannot be controlled independently.